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Oval tubes for photobioreactors: SCHOTT takes new approach to industrial cultivation of algae

New shape of the glass distributes light more evenly so that the microorganisms grow faster

The international technology group SCHOTT is conducting intensive research on the further development of photobioreactors (PBRs), and has now introduced a new approach for the industrial growing of algae. For this purpose, the manufacturer has developed an oval glass tube that is designed to help microorganisms grow more quickly. SCHOTT specialist Dr. Nikolaos Katsikis explains the idea, “We believe that the oval shape will distribute the light that algae need to carry out photosynthesis and grow much more evenly in PBRs. This will increase the yield.” Yet another benefit is that the oval shaped tubes from SCHOTT have a perfectly round shape at the ends so that they can be joined together using standard connectors to keep the cost low. SCHOTT is the only manufacturer capable of providing oval tubes with round ends for use in cultivating algae. SCHOTT will present this product innovation for the first time ever at the 7th annual Algae Biomass Summit in Orlando, Florida, (Sept. 30 to Oct. 3, 2013).

“We have already supplied initial tubes and are keeping a close eye on the test installations,” Katsikis. “We will then continue to improve our products based on the results.” According to Katsikis, the question of how the shape of the oval tube or the installation angle affects the growth of microorganisms is of particular interest. “We are the first manufacturer to offer this type of solution. Now, our goal is to set standards. We are therefore extremely interested in working together with other companies,” Katsikis added.

Background information: Algae third generation biomass

There are thousands of different types of algae all over the world today, of which approximately 100 to 200 can be industrially cultivated. The uses of algae and their metabolites are extremely diverse. They can serve not only as food, biofuels and fertilizers, but also as the ingredients of medications and cosmetics. Cultivating these microorganisms is described as third generation biomass because the process doesn’t take up farmland or compete with food production.

“There are essentially two different ways to cultivate algae industrially,” said Katsikis. “Open ponds seem to be rather inexpensive to build, but they have a number of drawbacks. The water in ponds evaporates and gets dirty over time. Foreign organisms can invade the ponds and interfere with algae production. Factors like these have a negative impact on yield.” On the other hand, he says that bioreactors that consist of rows of glass tubes of between 5 and 30 centimeters in diameter that are connected together offer significant advantages over open ponds. “The ideal conditions for algae exist in closed systems due to the fact that the process and all of the factors can be set more precisely,” said Katsikis. “This increases productivity and the quality of the harvest is also much higher.”

Process control offers many advantages

Due to the fact that the process can be controlled so well, the harvest results are highly reproducible. Algae can also be moved to another location quite easily —when a reactor needs to be cleaned, for example. This offers the operator greater flexibility with respect to production.

These advantages of process control and flexibility also play an important role in the latest trends in algae production. For example, carbon can be added as “food” for the algae inside a PBR and can be monitored more easily than in an open pond. Another trend calls for the light source to be optimized even to the point of distributing light via fiber optics within the algae culture. PBRs are better suited for this as well. Last, but not least, usually genetically modified algae can only be cultivated in closed systems.

When asked why the tubes are made of glass and not a synthetic material, Katsikis explains, “Tubes made of borosilicate glass are UV resistant and have been in use for well over 20 years without having to be replaced. These glass types can be up to 10 meters in length and, unlike plastics, do not require any additional support, which in turn lowers the cost. Glass is also scratch resistant and stands up to cleaning agents and utensils.

A broad portfolio from SCHOTT
SCHOTT offers algae farm operators a complete portfolio for PBRs. The portfolios include tubes with a variety of different wall thicknesses and interior diameters. The lengths vary from 1.4 to 10 meters. They also include U-shaped end pieces and connectors that can be modified to meet individual customer needs. The end pieces can also be used to connect glass and synthetic tubes. “In addition, we have significantly expanded the possibilities for our customers by launching these new oval tubes,” concluded Katsikis.
About SCHOTT
SCHOTT is an international technology group with more than 125 years of experience in the areas of specialty glasses and materials and advanced technologies. SCHOTT ranks number one in the world with many of its products. Its core markets are the household appliance, solar power, pharmaceuticals, electronics, optics, transportation and architecture industries. The company is strongly committed to contributing to its customers’ success and making SCHOTT an important part of people’s lives with high-quality products and intelligent solutions. SCHOTT is committed to managing its business in a sustainable manner and supporting its employees, society and the environment. The SCHOTT Group maintains close proximity to its customers with manufacturing and sales units in 35 countries. Its workforce of approximately 16,000 employees generated worldwide sales of $2.6 billion (approximately 2.0 billion euros) for the 2011/2012 fiscal year.